Boa

This is an experimental Javascript lexer, parser and interpreter written in Rust. Currently, it has support for some of the language.

Live Demo (WASM)

https://boa-dev.github.io/boa/playground/

You can get more verbose errors when running from the command line.

Development documentation

You can check the internal development docs at https://boa-dev.github.io/boa/doc.

Conformance

To know how much of the ECMAScript specification does Boa cover, you can check out results running the ECMASCript Test262 test suite here.

Contributing

Please, check the CONTRIBUTING.md file to know how to contribute in the project. You will need Rust installed and an editor. We have some configurations ready for VSCode.

Debugging

Check debugging.md for more info on debugging.

Web Assembly

This interpreter can be exposed to JavaScript! You can build the example locally with:

npm run build

In the console you can use window.evaluate to pass JavaScript in. To develop on the web assembly side you can run:

npm run serve

then go to http://localhost:8080.

Usage

• Clone this repo.
• Run with cargo run -- test.js where test.js is an existing JS file with any JS valid code.
• If any JS doesn't work then it's a bug. Please raise an issue!

Example

Command-line Options

Usage: boa [OPTIONS] [FILE]...

Arguments:
  [FILE]...
          The JavaScript file(s) to be evaluated

Options:
      --strict
          Run in strict mode

  -a, --dump-ast [<FORMAT>]
          Dump the AST to stdout with the given format

          Possible values:
          - debug:       The different types of format available for dumping
          - json
          - json-pretty

  -t, --trace
          Dump the AST to stdout with the given format

      --vi
          Use vi mode in the REPL

      --flowgraph [<FORMAT>]
          Generate instruction flowgraph. Default is Graphviz

          Possible values:
          - graphviz: Generates in graphviz format: <https://graphviz.org/>
          - mermaid:  Generates in mermaid format: <https://mermaid-js.github.io/mermaid/>

      --flowgraph-direction <FORMAT>
          Specifies the direction of the flowgraph. Default is TopToBottom

          [possible values: top-to-bottom, bottom-to-top, left-to-right, right-to-left]

  -h, --help
          Print help (see a summary with '-h')

  -V, --version
          Print version

Roadmap

See Milestones.

Benchmarks

See Benchmarks.

Profiling

See Profiling.

Changelog

See CHANGELOG.md.

Communication

Feel free to contact us on Discord.

License

This project is licensed under the Unlicense or MIT licenses, at your option.